Theoretical Study Of The Adsorption Of Magnetic Superatom On The Surface Of Carbon Nanostructures

Superatoms are stable clusters with special size and composition.They can not only simulate the chemical properties of individual atoms in the periodic table,but also can be used as basic building units to construct new functional materials.By rationally designing the size,constituent elements and geometrical structure of clusters,superatoms with novel properties can be obtained,which has become one of the hot topics in the research field of clusters.In this thesis,density functional theory(DFT)is used to systematically study the adsorption systems of magnetic superatom VM₈ on the surface of carbon nanostructures(graphdiyne and graphene)in terms of geometric structure,electronic structure,stability and magnetic moment changes of the superatoms.The main contents of this thesis are as follows:We use the density functional B3LYP method,combined with 6-31G(d)and the pseudopotential basis set lanl2dz(for V and Cs atoms)to perform all the calculations in this work.By taking into account different spin states,we have got adsorption configurations of superatoms VLi₈,VNa₈,VK₈,and VCs₈ on the surface of different carbon nanostructures(graphdiyne and graphene fragments),and systematically analyzed the interaction of magnetic superatoms VM₈ with graphdiyne and graphyne,as well as the structural characteristics,adsorption energy,HOMO-LUMO gap,charge transfer,and spin states of the adsorption systems.The results show that all the superatoms maintain their original configuration except for slight framework expansion after adsorbed on the surface of carbon nanostructures.According to the analysis of natural population,the magnetic superatoms lose electrons in the adsorption system,and the substrates gain electrons.The charge transfer interaction not only alters the electronic structure of the substrates,but also has the effect of enhancing the magnetic properties of certain superatom clusters.For example,Mulliken spin distribution shows that the magnetic moment of superatom VLi₈ increases from 5?_Bin the ground state to6.82?_Bafter adsorbed on the surface of GDY.Frontier molecular orbital analysis shows that,the HOMO orbitals of the VLi₈@GDY and VNa₈@GDY systems mainly overlay on the central V atom of the superatoms,while the LUMOs basically originate from the bottom GDY.In contrast,both superatoms and graphyne contribute to the frontier molecular orbitals of the VK₈@GDY and VCs₈@GDY systems.This study combines superatomic clusters with the surface of carbon nanostructures,and explores the formation mechanism and physicochemical properties of magnetic superatom assembly system in detail,which further embodies the application prospects of superatoms,and provides a new idea for the rational design of magnetic materials,especially magnetic thin film materials.It is also hoped to effectively promote the development and research of new magnetic nanomaterials.